Synthesis of three-dimensionally arranged porphyrin arrays via intramolecular meso–meso coupling

The synthesis and photophysical properties of three-dimensionally arranged porphyrin arrays with through-space electronic communication are reported. 1,3,5-Trioxamethylphenylene bridged Zn(II) porphyrin trimer 3 was coupled by Ag(I)-promoted oxidative coupling reaction to give porphyrin cage 5 comprising three meso–meso linked diporphyrins, which was then transformed by oxidation with DDQ and Sc(OTf)3 into porphyrin cage 7 comprising three fused diporphyrins. Intramolecular meso–meso coupling reaction was applied to porphyrin pentamer 11 to provide porphyrin array 12 consisting of a porphyrin core flanked by two meso–meso linked diporphyrins. Further oxidation of 12 with DDQ and Sc(OTf)3 afforded triply stacked porphyrin array 13 that is comprised of a porphyrin core flanked by two porphyrin tapes. UV–vis–NIR absorption and fluorescence spectra of 5, 7, 12, and 13 showed their distorted conformations and electronic interaction within the stacked porphyrin arrays.